Dry cleaning method



Feb. 1s, 1969 H, s, @.LBERT T AL 3,428,412

DRY CLEANING METHOD Filed April 27 1964 l `waff W www. maw ,WQ a@ .m/O rh em im v.. z 5

lla/ve conro//er/ United States Patent Otiice 3,428,412 Patented Feb. 18, 1969 3,428,412 DRY CLEANING METHOD Herman S. Gilbert, Angleton, and Nicholas B. Lorette, Lake Jackson, Tex., assignors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed Apr. 27, 1964, Ser. No. 362,898 U.S. Cl. 8-142 3 Claims Int. Cl. D061 1/02 This invention relates to an apparatus and method for cleaning fabrics by dry cleaning, and particularly to coin operated Idry cleaning apparatus and a method of operating such apparatus.

In so-called dry cleaning operations clothes or other fabrics are usually cleaned by agitating them while passing a non-aqueous solvent through them which often contains a detergent or soap and then extracting the solvent to dry the cleaned fabric.

The removed soils are either suspended or dissolved in the solvent used in the cleaning operation. Suspended materials are removed from the solvent by filtering, while dissolved soils are removed either by adsorption on activated carbon, by using so-called sweetener powders to change the fatty acids to soaps or by distilling the solvent.

While distilling the solvent is a desirable way to separate non-volatile matter vfrom the solvent, it is not really practical from an economic standpoint to |distill all the solvent used between each cleaning operation.

In many types of coin operated dry cleaning equipment, for example, up to 55 gallons or even more of solvent is used during each cycle of operation. It is too expensive in a highly competitive business such as the dry cleaning business to distill all of the solvent which is used during each cycle of operation. As a substitute it is known to dstill a small fraction of the solvent used during each cycle on an indiscriminant basis to remove the non-volatile materials `from the distilled solvent and thereby slow the buildup of non-volatile materials in the solvent inventory in the cleaning apparatus.

However, even though a small fraction of the solvent is distilled (on a non-selective basis from the base tank) during each cycle of operation of the dry cleaning apparatus, the removal of non-volatile materials from the solvent still occurs at a less rapid rate than is desirable.

Accordingly, a principal object of this invention is to provide an improved, economical metho'd and apparatus for removing non-volatile materials from the solvent in a dry cleaning system.

Another object of this invention is to provide an improved, simple to operate, economical apparatus and method for removing non-volatile materials from a predetermined portion of the solvent used in a dry cleaning operation.

In accordance with this invention there is provided means and a method for shunting into distilling apparatus at predetermined times a predetermined amount of the solvent which passes through the washing operation of the cleaning apparatus, and then returning the distilled solvent to a storage vessel. The solvent which is shunted into the distilling apparatus is that part of the solvent which contains the most dirt as a result of its contacting the fabric load in the cleaning apparatus.

`The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed `description is read in connection with the accompanying drawing, in which:

The single iigure shows, in simplified diagrammatical form, apparatus in accordance with this invention.

Referring to the drawing, there is shown dry cleaning apparatus, indicated generally by the numeral 10, which comprises a base tank 12, a wash wheel assembly 14 including an outer housing 16 and rotatable wash wheel 18, a filter 20, pump 22, condenser 24, heater 26, blower 28, solenoid controlled valves 36, 38, and distillation unit 40.

The filter 20 is coupled to a spray nozzle 42 within the housing 16 of the wash wheel assembly 14 by a hollow tube 44. The lilter 20 is also coupled to the Ibase tank 12 through hollow conduits 46, 48 and the pump 22.

A drain tube 50 having a valve 36 incorporated therein and which is coupled between the base tank 12 and the Wash wheel assembly 14 provides the main means for draining solvent from within the housing 16 of the wash wheel assembly to the base tank 12.

A drain tube 52 having a valve 38 incorporated therein is coupled from the drain tube 50 (between the valve 38 and the housing 16) to the distillation unit 40. The output line 54 from the distillation unit 40 is coupled to the line 56 which extends between the base tank 12 and the output of the condenser 24.

A gas and vapor circulation and extraction system, which includes the condenser 24, heater 26, and interconnecting tubing 56, 58, `60, 62, is coupled to the interior of the housing 16.

The tubing 62, blower 28 and tubing 58 connect the wash wheel housing 16 to the input 66 of the condenser 24. The tubing 60 extends from the condenser 24 through the heater 26 and back into the wash wheel housing 16.

In operation, as filtered solvent is pumped by means of the pump 22 through the nozzle 42 and onto the load of fabric (not shown) which is being tumbled by the rotating wash wheel 18, the solvent which has passed through or impinged on the fabric being cleaned usually returns from the housing 16 to the base tank 12 through the line r50 and valve 36.

However, during the part of the wash cycle in which the solvent contains the most soil, usually during the rst one to three minutes of the wash cycle, the valve 36 is closed, the valve 38 is opened, and a predetermined amount, around one gallon, for example, of solvent is flowed into the distillation unit 40. The valve 38 is then closed and the valve 36 is opened, and the remaining solvent drains from the wash wheel directly into the base tank through the line 50 and open valve 36.

Following the wash cycle, the wash wheel 18 is rotated at a rapid rate as is well known in the art to extract the solvent from the fabric load. Simultaneously, gas and vapors are drawn from the housing 16 by means of the blower 28 through the lines 62, 58. The vapors and gas from the line 58 are passed through the condenser 24, the solvent lquefying into droplets and dropping through the tube 56 .and thence into the base tank 12.

The uncondensed gas and vapors leave the condenser 24 through the line 60, passing through the heater 26 before returning to the wash wheel assembly 14, as is well known in the dry cleaning art. As the heated air re-enters the wash wheel bousing 16 additional solvent in the fabric is vaporized and withdrawn from the wash wheel assembly through the line 56 as described above.

Because the solvent which is passed into the distillation unit 40 contains a substantially larger amount of soil, especially non-volatile soils, than does the average similar amount -of solvent which leaves the wash wheel assembly, the distillation of this relatively small amount of solvent during each wash cycle provides a substantial improvement in solvent reconditioning over what is achieved when a similar amount of solvent, indescriminantly selected, is distilled.

The valve controller timer 32, coupled, as at A and B, to the solenoid valves 36, 38 actuates the valves 36, 38 to provide the flow of solvent to the distillation unit 40 at the appropriate time during the wash cycle. The particular time at which the solvent is most heavily laden with soil varies with diiferent types of cleaning apparatus, but usually occurs within 1/2 minute to 3 minutes after the washing cycle begins.

What is claimed is:

1. In a method of dry cleaning wherein liquid solvent is circulated from a base tank through soiled fabric and returned -to -said base tank, followed -by mechanically removing solvent from said fabric and then heating any solvent remaining in said fabric to dry said fabric, the steps comprising withdrawing a predetermined amount of said circulated solvent which has contacted said fabric and which contains the heaviest load of soil suspended or dissolved therein and then distilling said predetermined amount of soiled solvent Ibefore returning it to said base tank.

2. A method in accordance with claim 1, wherein said predetermined amount of solvent is withdrawn between the rst and third minute that said solvent is circulated through said fabric.

3. A method in accordance with claim 1, wherein said predetermined amount of circulated solvent is approximately one gallon.

References Cited UNITED STATES PATENTS 5 MAYER WEINBLATT, Primary Examiner. 

1. IN A METHOD OF DRY CLEANING WHEREIN LIQUID SOLVENT IS CIRCULATED FROM A BASE TANK THROUGH SOILED FABRIC AND RETURNED TO SAID BASE TANK, FOLLOWED BY MECHANICALLY REMOVING SOLVENT FROM SAID FABRIC AND THEN HEATING ANY SOLVENT REMAINING IN SAID FABRIC TO DRY SAID FABRIC, THE STEPS COMPRISING WITHDRAWING A PREDETERMINED AMOUNT OF SAID CIRCULATED SOLVENT WHICH HAS CONTACTED SAID FABRIC AND WHICH CONTAINS THE HEAVIEST LOAD OF SOIL SUSPENDED OR DISSOLVED THEREIN AND THEN DISTILLING SAID PREDETERMINED AMOUNT OF SOILED SOLVENT BEFORE RETURNING IT TO SAID BASE TANK. 